1. Field of the Invention
The present invention relates generally to the removal of organic deposits from the surface of sand particles. More particularly, the present invention relates to foundry operations and methods for removing molding compounds, carbonaceous materials and other organic deposits from sand particles which are utilized in the foundry operations.
2. Description of Related Art
Sand is commonly used in foundry operations to form a wide variety of molds used in casting and fabricating metal parts. During the molding process, the sand particles are coated with molding compounds which are necessary in order to form adequate mold surfaces. Upon completion of the molding process, the mold is destroyed leaving a pile of sand particles which are contaminated with molding compound, carbonaceous material and other organic deposits resulting from the molding process. These organic deposits render the sand unsuitable for further use in the foundry operations. As a result, large amounts of contaminated sand must be stored at the foundry location or transported to another location for disposal.
Processes have been developed in many foundries for recycling the sand particles. Such recycling processes involve heating of the sand particles to high temperatures in order to combust any organic deposits which may be present on the sand particles. In general, the sand particles are heated to relatively high temperatures for relatively long periods of time to insure complete combustion of the organic deposits. The heating process necessarily requires that the entire sand particle be heated to high temperature. As a result, large amounts of fuel must be burned to achieve sufficient heating to completely remove organic contaminants from the sand particles. The requirement of heating the entire sand particle also results in increased heating times and prolonged cooling times. The high energy demand and relatively cumbersome heating process are problems which have made this type of recycling process less than satisfactory.
It would be desirable to provide a simple, quick and efficient technique for removing molding compound and other organic deposits from sand produced in foundry operations. The process should be amenable to treating the large amounts of sand produced in a typical commercial scale foundry operation in a simple and energy efficient manner.